Method for determining chemical structure of lipid and ion mobility-tandem mass spectrometer

Abstract

The present disclosure relates to the field of mass spectrometry, and particularly provides a method for determining a chemical structure of a lipid and an ion mobility-tandem mass spectrometer. The method for determining a chemical structure of a lipid includes: an ionization step of ionizing a sample to obtain sample ions; an ion mobility-based separation step of separating target lipid ions from the sample ions based on ion mobility; a first dissociation step of dissociating the target lipid ions with dissociation energy adjusted to break a first chemical bond of the target lipid ions; a mass-based selection step of selecting the target lipid ions, whose first chemical bond is broken, based on a mass number to obtain fragment ions; a second dissociation step of dissociating the fragment ions to at least break a second chemical bond of the fragment ions which has bond energy higher than the first chemical bond, to obtain diagnostic ions; and a mass analysis step of performing a mass analysis on the diagnostic ions.

1 . A method for determining a chemical structure of a lipid, the method comprising:
 an ionization step of ionizing a sample to obtain sample ions;   an ion mobility-based separation step of separating target lipid ions from the sample ions based on ion mobility;   a first dissociation step of dissociating the target lipid ions with dissociation energy adjusted to break a first chemical bond of the target lipid ions;   a mass-based selection step of selecting the target lipid ions, whose first chemical bond is broken, based on a mass number to obtain fragment ions;   a second dissociation step of dissociating the fragment ions to at least break a second chemical bond of the fragment ions which has bond energy higher than the first chemical bond, to obtain diagnostic ions; and   a mass analysis step of performing a mass analysis on the diagnostic ions.   
     
     
         2 . The method for determining a chemical structure of a lipid according to  claim 1 , wherein the lipid is an unsaturated lipid having a carbon-carbon double bond in a fatty acyl chain, and the method is used for identifying a position of the carbon-carbon double bond in the fatty acyl chain and a sn-position of the fatty acyl chain. 
     
     
         3 . The method for determining a chemical structure of a lipid according to  claim 2 , further comprising, before the ionization step:
 a derivatization reaction step of labeling the carbon-carbon double bond using a derivatization reaction.   
     
     
         4 . The method for determining a chemical structure of a lipid according to  claim 3 , wherein the lipid is a phospholipid or a sphingolipid, the first chemical bond is a polar head group of the phospholipid or a polar head group of the sphingolipid, and the second chemical bond is a chemical bond generated from derivatization of the carbon-carbon double bond. 
     
     
         5 . The method for determining a chemical structure of a lipid according to  claim 3 , wherein the derivatization reaction is an aziridination reaction, an epoxidation reaction, a Paternò-Büchi reaction, a singlet oxygen-ene reaction, or a Diels-Alder reaction. 
     
     
         6 . The method for determining a chemical structure of a lipid according to  claim 1 , wherein the lipid is a fatty acid, a glycerolipid, a glycerophospholipid, a sphingolipid, a sterol lipid, a prenol lipid, a saccharolipid, or a polyketide. 
     
     
         7 . The method for determining a chemical structure of a lipid according to  claim 1 , further comprising:
 a first pre-scan step of performing a mass analysis on the sample ions that are not subjected to the first dissociation step and the second dissociation step.   
     
     
         8 . The method for determining a chemical structure of a lipid according to  claim 1 , further comprising:
 a second pre-scan step of performing a mass analysis on the sample ions that are subjected to only one dissociation.   
     
     
         9 . An ion mobility-tandem mass spectrometer comprising:
 an ion source configured to ionize a sample to obtain sample ions;   an ion mobility spectrometer configured to separate target lipid ions from the sample ions;   a first dissociation device configured to dissociate the target lipid ions, in which dissociation energy is adjusted to break a first chemical bond of the target lipid ions;   a mass filter configured to select the target lipid ions, whose first chemical bond is broken, to obtain fragment ions;   a second dissociation device configured to dissociate the fragment ions to at least break a second chemical bond of the fragment ions which has bond energy higher than that of the first chemical bond to obtain diagnostic ions; and   a mass analyzer configured to perform a mass analysis on the diagnostic ions.   
     
     
         10 . The ion mobility-tandem mass spectrometer according to  claim 9 , wherein the ion mobility spectrometer is a U-shaped ion mobility spectrometer. 
     
     
         11 . The ion mobility-tandem mass spectrometer according to  claim 10 , wherein the U-shaped ion mobility spectrometer operates in a filter mode. 
     
     
         12 . The ion mobility-tandem mass spectrometer according to  claim 9 , wherein the mass filter is a quadrupole or an ion trap. 
     
     
         13 . The ion mobility-tandem mass spectrometer according to  claim 9 , wherein the mass analyzer is a time-of-flight mass analyzer, a Fourier transform mass spectrometer, a quadrupole mass analyzer, an ion trap mass analyzer, or a magnetic mass spectrometer. 
     
     
         14 . The ion mobility-tandem mass spectrometer according to  claim 9 , wherein the ion source is an electrospray ionization source, a nanoelectrospray ionization source, a desorption electrospray ionization source, an atmospheric pressure chemical ionization source, an atmospheric pressure photoionization source, or a matrix-assisted laser desorption ionization source. 
     
     
         15 . The ion mobility-tandem mass spectrometer according to  claim 9 , wherein the first dissociation device and/or the second dissociation device are/is one or more of a high-energy collision dissociation device, a collision-induced dissociation device, an oxygen-attachment dissociation device, a hydrogen-attachment dissociation device, an electron-capture dissociation device, a radical-directed dissociation device, an ultraviolet photodissociation device, and a charge-remote fragmentation device. 
     
     
         16 . The ion mobility-tandem mass spectrometer according to  claim 15 , wherein the first dissociation device is a collision-induced dissociation device and has a terminal electrode voltage of 10 eV to 70 eV, and the second dissociation device is a collision-induced dissociation device and has dissociation energy of 30 eV to 70 eV. 
     
     
         17 . The ion mobility-tandem mass spectrometer according to  claim 9 , further comprising: a separation device disposed at a preceding stage of the ion source, wherein the separation device is one or more of a liquid chromatograph, a gas chromatograph, a supercritical fluid chromatograph, a capillary electrophoresis device, and a paper chromatograph.